Biology: Levels of Organization - Chapter 3, Lesson 2 PDF

**Chapter 3: From a Cell to an Organism** **Lesson 2: Levels of Organization** Remember multicellular organism means many cells. - Grow by making more small cells (not by making cells larger) - These cells work together to perform certain functions in the body. - Benefits - Larger...

**Chapter 3: From a Cell to an Organism** **Lesson 2: Levels of Organization** Remember multicellular organism means many cells. - Grow by making more small cells (not by making cells larger) - These cells work together to perform certain functions in the body. - Benefits - Larger size: larger than single-celled organisms - Longer life - Specialization: makes the organism more efficient Remember unicellular organism means only one cell. - This one cell carries out all activities necessary to survive. - Organisms respond to their environment, get rid of wastes, grow, and reproduce on their own Prokaryotes -- a cell without a membrane-bound nucleus - Smaller than eukaryotic cells - Example: bacteria Eukaryotes -- a cell that has a nucleus surrounded by a membrane and many other specialized organelles - Example: plants and animals **Cell differentiation:** the process by which cells become different types of cells - All cells in a multicellular organism come from one cell -- a fertilized egg from an egg cell and sperm cell - Cells can become nerve, red blood, bone, or muscle cells (to name a few). **Stem cells:** unspecialized cells that are able to develop into many different cell types - There are more stem cells in embryos than in adult organisms - Adult stem cells are important for cell repair and replacement - Can be found in bone marrow and skeletal muscles - Plants also have unspecialized cells in areas called meristems **Tissue:** groups of similar types of cells that work together to perform a specific task - Animals have four basic types of tissues - Nervous tissue carries messages to and from the brain - Muscle tissue cause movement - Connective tissue provides structure and support and connects other types of tissue together - Epithelial tissues form the protective outer layer of the skin and the lining of major organs and internal body cavities - Plants have three basic types of tissues - Dermal tissue provides protection and helps reduce water loss - Vascular tissue transports water and nutrients from one part of the plant to another - Ground tissue provides storage and support and where photosynthesis takes place **Organ:** groups of different tissues working together to perform a particular job - Ex. Humans...heart, stomach - Ex. Plants...leaves, stems, roots **Organ system:** a group of different organs that work together to complete a series of tasks - Each organ system has a specific job to do in the body and can be made up of many different organs - Example: digestive system (include the stomach, small intestine, live, and large intestine) and cardiovascular system - Plants have 2 major organ systems -- the shoot system (leaves, stems, and flowers) and root system (anchors the plant and takes in water and nutrients) **Organism:** anything that can perform life processes - *The human body has many major organ systems (skeletal, respiratory, circulatory, muscular, nervous, and digestive systems)* - *Each organ system depends on the other systems and cannot work alone.*